European Journal of Wood and Wood Products最新文献

Agarwood oil is considered to be one of the costliest essential oils, produced by hydro-distillation of agarwood chips from resin impregnated wood from Aquilaria spp. Prior to distillation, the traditional production process involves a prolonged (up to 90 days) soaking of the wood in water filled basins. This natural fermentation step exposes the wood to interactions with different types of microorganisms like in mixed culture fermentation. Reports have suggested a definite role of fermentation on the qualitative and quantitative properties of the distilled oil. However, these studies relied on single organism led fermentation. The present study explores the consortia approach as a method to enhance the aroma of the oil, simulating natural fermentation. Enzyme activity based screening and co-culture interaction studies were employed to develop three (3) fungal and seven (7) microbial (bacteria-fungi) two-member consortia from microorganisms isolated from traditional agarwood fermentation basins located in Assam, India. The effect of consortia on agarwood oil was validated by fermentation with agarwood chips. Among the fungal consortia, 20PW (Pupureocillium lilacinum) with PG120 (Penicillium aethiopicum) and among bacteria- fungi consortia NH7 (Microbacterium oxydans) with PG120 (Penicillium aethiopicum), showed promising results. GC–MS analysis revealed qualitative enhancement of oil by all consortia compared to the control for key aroma compounds such as Agarospirol, Guaiol, 10S, 11SHimachala-3(12), 4-diene and Aristol-1(10)-en-9-ol. This is the first report where microbial consortia were used for the fermentation of agarwood chips, which enhance the quality of agarwood essential oil.

Lightweight structures are of paramount importance in engineering applications. Optimal designs combining various optimization techniques can maximize desired mechanical characteristics while minimizing undesired static or dynamic behaviors. However, these optimized structures usually have low safety factors, which makes it necessary to consider uncertainties in project design to ensure their reliability. This paper presents a systematic approach to quantify uncertainties in an optimized structural member of an unmanned aerial vehicle (UAV) wing used in remote sensing. The UAV wing structural member was optimized using the Multi-Objective Genetic Algorithm, and balsa wood, a lightweight and ecological material with high variability in mechanical properties, was used for its manufacture. To analyze the structural integrity of the UAV wing, the present study quantified parametric uncertainties in material properties and manufacturing processes using stochastic models. A probabilistic approach was adopted, which revealed a 37% reduction in the structure's safety coefficient. Various conclusions were drawn from this research, which highlights the importance of considering uncertainties in the design of optimized structures to ensure their reliability.

Veneer knots are the main indicator of plywood quality. Existing veneer knot identification algorithms have a high identification accuracy rate of over 90%. However, the convolutional neural network (CNN) model is complex and requires laborious data labeling. The localization algorithm produces veneer knot bounding boxes, except for the Mask Region-based CNN (Mask R-CNN) model, which is not accurate and has error transmission. Additionally, the calculation of defect size (area and diameter) has not been addressed. This paper proposes a parallel structured fusion algorithm. One branch employs a classical simple CNN, specifically the Inception V3 network, to identify veneer knot defects. The other branch proposes an improved K-means clustering algorithm to localize veneer knot defects. After identification and localization are achieved, the actual area of the defect is calculated. The proposed method for identifying veneer knot defects has an accuracy rate of 99.61%. The size accuracy localization rate is 94%, with an under-sized localization rate of 2%, an over-sized localization rate of 3%, and the knot localization error rate is 1%. Additionally, the algorithm also calculates the area and diameter of the knot, with a mean absolute error of the diameter of 3.23 mm. This paper presents an algorithm with low complexity, fast speed, high accuracy, and no error transmission, making it suitable for identifying and localizing other defects.

Making furniture or furniture elements that account for the needs of children at various stages of development or with psychomotor dysfunctions is very difficult. From the point of view of exploitation and production technology, it is difficult to select a specific material and manufacturing technique. In this article, the results of using the APEKS method, which is a type of Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method, are presented to select the best solution for the production of children’s furniture elements with surface structures similar to those of natural materials. Wood bark was selected as a material that, due to the sensory tactile sensations of dysfunctional children, could contribute to therapy and education. Comparative analysis was performed on the basis of the subtractive and additive methods used for manufacturing furniture products. Precise multiaxis milling of ash wood and 3D printing with fused filament fabrication technology using wood PLA filaments were carried out. The method used to select the best option considered quantitative and qualitative criteria in the assessment. Various parameters characterizing the surfaces were analyzed, such as geometric dimensions, hill heights, valley depths, and 3D surface parameters. The quality and surface roughness (Sa, Sz, Ssk, Sku, Sp, and Sv) parameters obtained based on 3D microscope measurements were determined. A scale of 1 to 10 was used to assess qualitative factors (i.e., usability and aesthetics). Based on the critical values obtained from the coefficient K_cri = 79.36, it was assumed that multiaxis wood milling was the best method for producing furniture elements with the required surface characteristics for use as therapeutic and educational tools for children with dysfunctions. The applied method allowed an effective evaluation of the compared variants of the production of furniture elements for customized applications.

The increasing demand for wood with enhanced flame retardant characteristics in construction applications necessitates strategic interventions. This study explores the fire behaviour and chemical characterisation of Robinia pseudoacacia wood subjected to thermal modification and flame retardant treatments. Thermal modification was carried out at three different temperatures (160 °C, 180 °C and 240 °C). The fire properties of wood coated with Flame Gard (F), a commercial flame retardant, arabinogalactan (A), a natural flame retardant, melamine adhesive (MF) with ammonium polyphosphate (AP), nanosilica (NS), nanoclay (NC) (MF-AP-NS and MF-AP-NC) and arabinogalactan with AP, NS and NC (A-AP-NS and A-AP-NC), were assessed using cone calorimetry in terms of the weight loss rate, ignition time and heat release rate. The commercial flame retardant Flame Gard outperformed the natural and fortified flame retardants in terms of the weight loss rate, heat release rate (HRR) and ignition time (t_ig). Unmodified samples exhibited superior fire properties in terms of t_ig and HRR compared to thermally modified samples. The peak heat release rate (kW.m^− 2) and time to peak heat release rate (s) showed a moderate degree of dependency on the chemical constituents of the wood.

Location determines not only the climatic condition but also the structural loads that the structure must withstand. Given the broad variety of climatic and seismic requirements of Chile, the design of lightweight timber buildings considering both energy and seismic design parameters and boundary conditions becomes a difficult task. The main objective of this research is to analyze and quantify the effect of climates, seismic loads, lateral anchorage, and story number on the optimal energy design solutions, including the seismic behavior in a light-frame timber building. Furthermore, the optimal design was parametrically analyzed considering five Chilean cities that consider different climates, seismic zone, number of stories, and lateral anchorage systems to prevent rocking (overturning) due to lateral seismic forces. The optimal wall insulation thickness, stud spacing, and thermal mass exhibited significant variations depending on the buildings' number of stories, lateral anchorage system, climate, and seismic zone. Therefore, the results of this investigation reinforce the necessity of integrating energy and seismic designs for light-frame timber buildings. The optimal designs obtained in this investigation showed considerable variations depending on the combination of climatic and seismic loads as well as the number of stories and anchoring systems. The article's main contributions are the evidence of the structural and energy design interconnection of light-frame timber buildings and how design variables, such as stud spacing, floor concrete thickness layer, and wall insulation thickness, are related and change according to the different climates, seismic loads, lateral anchorage, and story number.

A major function of resin in trees is to provide defense against external attacks by releasing the resin flow in the attacked or damaged area. Nonetheless, leakage of resin on the surface can have negative aesthetic and economic impacts on wood materials. The aim of this study was to investigate how heat treatment affects the physico-chemical properties of the resin of Pinus sylvestris L. to hinder exudation on wood surfaces during service. To reduce the fluidity of the resin, it is necessary to remove the volatile fraction of resin, and several studies have been carried out in this direction, providing useful information about this process. The results from thermal analyses (DSC, TGA) confirmed that heat treatment at mild temperatures, 80 °C, 90 °C and 100 °C had a positive effect on increasing the glass transition temperature T_g and that the T_g and the residual volatile content were strongly correlated. FTIR spectroscopy, before and after heat treatment, did not reveal major changes in chemical structure, while UHPLC-DAD-MS analysis revealed significant differences in the ratios of compounds, which are the result of possible chemical reactions, such as dehydrogenation, oxidation and isomerization.

Laminated bamboo columns with box sections are favored by designers because they overcome the disadvantage of small elastic modulus, but local buckling behavior caused by an excessive width-to-thickness ratio will lead to a non-uniform distribution of stress. The discontinuous cracks at the glued joints and waveform deformation indicate that the local buckling has a significant effect on the bearing capacity of columns with box sections. However, few studies have been reported on the evaluation of bearing capacity considering local stability due to non-uniformity and discontinuity. The experiments on 5 glued laminated bamboo columns with box sections (GLBCs) with different length-to-width ratios under axial compression were carried out. The test results showed that the waveform bulging failure occurred on the surface of GLBCs before the overall buckling, and an obvious debonding failure occurred between the bamboo plates. These failures aggravated the local buckling failure. As the length-to-width ratio increased, the number of waveforms buckling increased, the lower the bearing capacity. To evaluate the local stability of GLBCs accurately, a new anisotropic plate model considering the width correction coefficient and material anisotropy for the critical buckling load of GLBC was proposed. Furthermore, it can be found that an appropriate width-to-thickness ratio can effectively avoid local buckling failure. A formula for the critical width-to-thickness ratio of GLBCs under different slenderness ratios was proposed. In this paper, the anisotropic plate model proposed can accurately evaluate the bearing capacity considering the local stability of GLBCs under axial compression.

The study addresses concerns associated with formaldehyde-based adhesives in wood panel board production by proposing geopolymer-based wood binders as promising, formaldehyde-free alternatives. Using bentonite, the research delves into the development and performance properties of this geopolymer wood binder. The BET method was employed for the surface characterization of precursor raw materials for binder preparation. Si and Al elements identified through XRF analysis were correlated with characteristic bands in the FTIR spectrum. Alkaline activation solutions, employing sodium silicate and sodium hydroxide with a molar ratio range of 0.5 to 2.5 (SiO₂:Na₂O), revealed that binders with a molar ratio of 2.5 exhibited lower pH and higher adhesion strength. Different geopolymer formulations at solution to powder ratios (s/p) of 1.33, 3, and 3.5 determined s/p 3.5 as optimal for bentonite-based organo-geopolymer binders. Viscosity, gel time, pH, and solids content were examined, showing the effectiveness of substituting 10% silica fume to enhance the geopolymerization process and improve adhesion. Modifications using citric acid, sucrose, paraffin, pMDI, triacetin, and resorcinol demonstrated wet bonding strength comparable to urea formaldehyde adhesive. Analytical techniques, including FTIR spectroscopy, XRD analysis, and SEM EDX analysis, provided insights into functional groups, crystallographic properties, and microstructural characteristics. The concentration of Si and Al compounds on the bonding line, coupled with Na element diffusion, was observed through these analyses. Light microscopy of lap shear samples revealed a thinner bonding line, affirming effective binder penetration into wood cell lumens in bentonite-based organo-geopolymer binder formulations.